Lucent Technologies Inc.

Digital Equipment Corporation

Alcatel-lucent USA Inc.

John Rigby

Michael J Seaman

Stewart F Bryant

Prashanth Ishwar

Andrew J Walton

Una M Quinlan

Fearghal Morgan

Joseph O'Callaghan

Apurva Mehta

James Jiahua Yu

Krishna Sankaran

Ramanarayanan Ramakrishnan

Shiva Shenoy

Mike Morrison

Rahul Kasralikar

Thippanna Hongal

Ramanaravanan Ramakrishnan

Krishnan Sankaran

Rahul S Kasralikar

Path information is obtained in a VPLS-based network by generating special Layer 2 frames (referred to herein as 'trace-request frames'), performing source MAC filtering to identify the trace-request frames, and generating a special frame (referred to herein as a 'trace-reply frame') when the source MAC filtering identifies a trace-request frame. Upon identifying a trace-request frame, path information is collected and embedded into the trace-reply frame. The trace-reply frame is then sent to the originating node where the path information is used to learn the path that the trace-request frame traversed. By sending multiple trace-request frames with different source MAC addresses, path information received from source MAC filtering at different nodes in the VPLS-based network can be collected and used to learn an entire path of interest.

Obtaining path information related to a virtual private LAN services (VPLS) based network

A technique for classifying traffic at a network node involves programming a content addressable memory (CAM) array with multiple class-specific entries, where each of the class-specific entries has an associated traffic class, obtaining a protocol-independent key field from an incoming packet, and searching the programmed CAM array with the protocol-independent key field to identify an associated traffic class of the incoming packet. In another embodiment, each of the class-specific entries has an associated traffic distribution policy, which may be applied to an incoming packet.

Classifying and distributing traffic at a network node

Protection switching between primary and secondary paths in a packet-based network involves table entries that are pre-programmed with a primary path, a secondary path, and a value that identifies the primary path, referred to as a primary path identifier (PPI). When table entries are accessed to make forwarding decisions, the PPI is compared to a field that identifies that a particular path is down, referred to as a down path identifier (DPI). If the two fields match, (i.e., PPI=DPI), then the secondary path is selected instead of the primary path as the path on which the traffic should be forwarded.

Protection switching at a network node

The present invention provides an interlock scheme for use between a line card and an address recognition apparatus. The interlock scheme reduces the total number of read/write operations over a backplane bus coupling the line card to the address recognition apparatus required to complete a request/response transfer. Thus, the line card and address recognition apparatus are able to perform a large amount of request/response transfers with a high level of system efficiency. Generally, the interlocking scheme according to the present invention merges each ownership information storage location into the location of the request/response memory utilized to store the corresponding request/response pair to reduce data transfer traffic over the backplane bus. According to another feature of the interlock scheme of the present invention, each of the line card and the address recognition engine includes a table for storing information relating to a plurality of database specifiers. Each of the database specifiers contains control information for the traversal of a lookup database used by the address recognition apparatus. At the time the processor of a line card generates a request for the address recognition apparatus, it will analyze the protocol type information contained in the header of a data packet. The processor will utilize the protocol type information as a look-up index to its table of database specifiers for selection of one of the database specifiers. The processor will then insert an identification of the selected database specifier into the request with the network address extracted from the data packet.

Scheme for interlocking line card to an address recognition engine to

The present invention is directed to an address recognition apparatus including an address recognition engine coupled to a look-up database. The look-up database is arranged to store network information relating to network addresses. The look-up database includes a primary database and a secondary database. The address recognition engine accepts as an input a network address for which network information is required. The address recognition engine uses the network address as an index to the primary database. The primary database comprises a multiway tree node structure (TRIE) arranged for traversal of the nodes as a function of preselected segments of the network address and in a fixed sequence of the segments to locate a pointer to an entry in the secondary database. The entry in the secondary database pointed to by the primary database pointer contains the network information corresponding to the network address. The address recognition engine includes a table for storing a plurality of database specifiers. Each of the database specifiers contains control information for the traversal of the primary and secondary databases. In addition, each of the nodes in the primary database and each of the entries in the secondary database is provided with control data structures that are programmable to control the traversal of the database.

Address recognition engine with look-up database for storing network

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Reading, United Kingdom

John Rigby